Supergravity pp-wave solutions with 28 and 24 supercharges

We conduct an exhaustive search for solutions of type IIA and IIB supergravity with augmented supersymmetry. We find a two-parameter family of type IIB solutions preserving 28 supercharges, as well as several other type IIA and IIB families of solutions with 24 supercharges. Given the simplicity of the pp-wave solution, the algorithm described here represents a systematic way of classifying all such solutions with augmented supersymmetry. By T dualizing some of these solutions we obtain exact non-pp-wave supergravity solutions (with 8 or 16 supercharges), which can be interpreted as perturbations of the AdS-CFT correspondence with irrelevant operators.